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Beige Power Mac G3 Benchmarks

Daniel Knight - 2002.01.22

For months now, the Beige Power Mac G3 has been the most popular profile on Low End Mac, indicating to us that it’s the hottest low-end Mac out there. We recently rated it a Low End Mac Best Buy – but with reservations if you plan to run Mac OS X.

We picked up a beige 266 MHz Beige Power Mac G3 in January 2002 as our testbed machine for learning Mac OS X – and seeing how well (or poorly) OS X does on a slower, older Mac with poorly supported graphics acceleration.

Before doing that, we wanted to run the usual benchmarks. The CPU runs at 267.28 MHz with a 512 KB level 2 (L2) cache running at half that speed and a 66.82 MHz system bus, half as fast as the L2 cache. The computer has 288 MB of RAM installed. The installed hard drive is a Quantum Fireball SE 4.3A.

This is by far the most comprehensive set of benchmarks we’ve published yet, ranging from Mac OS 8.1 through 9.2.2 and covering various disk cache sizes with virtual memory on and off to see which settings provide the best performance.

Speedometer 3.06

The system was tested on 2002.01.21 using a full install of Mac OS 8.1. The computer was attached to a 12″ mono monitor and tested in 8-bit video mode at 640 x 480 resolution. Results are relative to a Mac SE or Classic, which rates 1.0. Numbers are rounded off to one or two decimal places.

Keep in mind that Speedometer 3.06 is written for the old 68K Macs and runs in emulation on Power Macs.

The first set of numbers compares performance at different cache settings with virtual memory disabled.

The cache setting should have little influence on non-disk tests, which these numbers bear out. With this particular setup, cache size makes only a small difference in performance – even disk performance beyond the 128 KB mark. At least as far as Speedometer 3 is concerned, a 256 KB or 512 KB disk cache seems optimal under OS 8.1.

There are several claims about virtual memory (VM). One is that setting VM to 1 MB more than physical RAM (in this case, setting it to 289 MB) provides the best balance of speed and efficient memory use. Others claim the best results come when VM is set to a multiple of 32 MB. Still others, that making VM double installed RAM is best.

The following results are for VM off, on at 289 MB, on at 320 MB, and on at 576 MB, all using a 256 KB disk cache.

These figures give some credence to the argument that some VM settings are better than others. The graphics score takes a reduction with VM enabled, and the CPU score drops 7% at the 320 MB setting, while the disk score is better at 320 MB with VM on than with VM set to 1 MB above RAM. Going to 576 MB VM reduced everything except the CPU score. Best overall results with Speedometer 3 and OS 8.1 are with VM disabled.

We next updated the Beige G3 to Mac OS 9.0, turned off virtual memory, restored the disk cache to 256 KB, ran Norton Utilities and Speed Disk on the drive, and began our next round of OS benchmarks, using various versions of OS 9.x as well as testing with VM on (at 320 MB) and with the default (a massive 8 MB) disk cache. Here are our results:

This Mac performs as well on the disk benchmark without VM on OS 9.0 as it did on 8.1 with VM on – and sees still better disk performance when VM is enabled. The default 8 MB disk cache under OS 8.5 and later really boosts disk performance. Under 9.0, overall best disk performance comes with the default cache and VM off.

Moving from 9.0 to 9.1, we regain the graphics performance lost going from 8.1 to 9.0, although math performance drops about 1%. Upgrading to Mac OS 9.2.2 surprisingly drops the CPU score without VM to match that with VM enabled – I retested to make sure it wasn’t a fluke.

Next we go full circle and test the various disk cache and VM settings under Mac OS 9.2.2. The first set of tests is run with VM off.

All things considered, we’d give VM off a small edge here. It has the best score in two benchmarks and takes second place for disk performance. Overall, though, results are quite close except for the 8.43 disk score with VM set at 576 MB.

Based on these two sets of results, we can expect the best overall performance with VM disabled and the default cache, but which VM setting will provide the best overall results with an 8 MB disk cache?

If you are going to use virtual memory under Mac OS 9.2.2, you’ll get the best overall results by setting VM to the next multiple of 32 greater than the amount of physical RAM installed in your computer. Your next best bet is to set VM at twice physical RAM.

Speedometer 4.02

The system was tested on 2002.01.21 under a full install of Mac OS 8.1. The computer was attached to a 12″ mono monitor and tested in 8-bit video mode at 640 x 480 resolution. Results are relative to a Quadra 605, which rates 1.0. Numbers are rounded off to one or two decimal places.

The first set of numbers compares performance at different cache settings. (Because Power Macs don’t support 1-, 2-, or 4-bit video, Speedometer 4 was unable to test the graphics.) Virtual memory was disabled for these tests.

The cache setting should have little influence on non-disk tests, which these numbers bear out. As above, with this particular setup, cache size makes no significant difference, except that the disk score is a bit lower with a 96 KB cache. As with Speedometer 3, we’d call a 256 KB or 512 KB disk cache optimal under Mac OS 8.1.

There are several claims about virtual memory. One is that setting VM to 1 MB more than physical RAM (in this case, to 289 MB) provides the best balance of speed and efficient memory use. Others claim the best results come when VM is set to a multiple of 32 MB. Still others, that making VM double installed RAM is best.

The following results are for VM off, on at 289 MB, on at 320 MB, and on at 576 MB using a 256 KB disk cache.

These figures give some credence to the argument that some VM settings are better than others. While Speedometer 4 measures an insignificant difference between no VM and VM set at 289 MB, changing that setting to 320 MB dramatically boosts the disk score by one-third! However, all three tests were lower at the 576 MB setting. Because of the significantly improved disk score at 320 MB, we’d call that the best setting for OS 8.1 and Speedometer 4.

We next updated the Beige G3 to Mac OS 9.0, turned off virtual memory, restored the disk cache to 256 KB, ran Norton Utilities and Speed Disk on the drive, and began our OS benchmarks. Here are our results:

Where OS 8.0 saw a 33% boost in hard drive performance with VM enabled, OS 9.0 saw a much smaller 4.5% improvement at the same 256 KB setting. Under Speedometer 4, there is virtually no difference between the disk scores when using the default 8 MB disk cache.

There is a very small drop in CPU and math performance (0.4%) going to OS 9.1; it’s certainly nothing you’d ever notice.

Next we go full circle and test the various disk cache and VM settings under Mac OS 9.2.2. This group of results shows the effect of the disk cache with VM off.

Speedometer 4 doesn’t find a significant difference in CPU or math scores whether the disk cache is big or small, so we’ll give the win to the 8 MB default cache setting because of the better disk score.

The next group of benchmarks measures performance with a 256 KB disk cache and various VM settings.

Speedometer 4 finds an insignificant difference among CPU and math scores under Mac OS 9.2.2, so we’d have to give the nod to VM set at 576 MB because of the significantly better disk score.

Based on these two sets of results, we can expect the best overall performance with VM disabled and the default cache, but which VM setting will provide the best overall results with an 8 MB disk cache?

If you are going to use virtual memory under Mac OS 9.2.2, your optimal setting will be the next multiple of 32 greater than the amount of physical RAM installed, although that barely edges out double physical RAM as far as Speedometer 4 is concerned.

MacBench 5

The system was tested on 2002.01.21 using a normal installation of Mac OS 8.1. The computer was attached to a 12″ mono monitor and tested in 8-bit video mode at 640 x 480 resolution. The disk cache was set to 256 KB for all tests. Results are relative to a 300 MHz Beige Power Mac G3, which scores 1000.

Virtual memory was turned off. Graphics tests could not be run on this setup, since the monitor does not support 800 x 600.

Unlike the Speedometer tests, where a 128 KB cache was just 2-3% faster than a 96 KB cache, that seemingly small change made a 67% improvement under MacBench 5. Growing the cache beyond 256 KB also improved performance under MacBench 5, which uses a larger test file than either version of Speedometer. For MacBench 5 and Mac OS 8.1, a 512 KB or 1 MB disk cache seems to provide the best overall results.

There are several claims about virtual memory. One is that setting VM to 1 MB more than physical RAM (in this case, to 289 MB) provides the best balance of speed and efficient memory use. Others claim the best results come when VM is set to a multiple of 32 MB. Still others, that making VM double installed RAM is best.

The following results are for VM off, on at 289 MB, on at 320 MB, and on at 576 MB using a 256K disk cache.

MacBench 5 finds a measurable (7%) reduction in CPU performance with VM enabled in OS 8.1, along with a small (3%) decrease in drive performance, and no significant change in math performance (well under 1%). Although some claim disk performance improves when VM is used, MacBench 5 belies that claim. Among these settings, running with VM off seems optimal for MacBench 5 and Mac OS 8.1.

We next updated the Beige G3 to Mac OS 9.0, turned off virtual memory, restored the disk cache to 256 KB, ran Norton Utilities and Speed Disk on the drive, and began our OS benchmarks. Here are our results:

Perhaps the biggest improvement in OS 9.0 is the 3% higher CPU score when VM is enabled, showing an improvement in the underlying VM mechanism. Curiously, we see a 3-4% drop in the CPU benchmark going from 9.0 to 9.1 but almost no change (under 0.5%) in the math score.

Next we go full circle and test the various disk cache and VM settings under Mac OS 9.2.2. The following tests were run with VM off and various disk cache sizes.

As before, the best CPU score was obtained with a 256 KB disk cache, although the range of CPU scores is very tight (about 0.6%), as is the range of math scores. All things considered, the best overall performance goes to the setting with the best disk score, and a larger cache always provides a better drive score.

This set of results was obtained with a 256 KB disk cache and various VM settings.

Looking over these results, we find that MacBench 5.0 has the best overall scores with VM disabled.

Based on these two sets of results, we can expect the best overall performance with VM disabled and the default cache, but which VM setting will provide the best overall results with an 8 MB disk cache?

If you are going to use virtual memory under Mac OS 9.2.2, these tests indicate that you’ll achieve the best results by setting VM at the next multiple of 32 higher than the amount of physical RAM installed in your Mac or double the amount of physical RAM installed – it’s pretty much a toss-up this time around.

Conclusion

Each benchmark works differently, but these tests indicate that the disk cache should be set to at least 128 KB for decent results and 512 KB for better ones. As for virtual memory, the results are a mixed bag. We have turned conventional wisdom on its head – setting VM to 1 MB over installed RAM and to twice installed RAM are both generally inferior to using a VM setting that is the next multiple of 32 higher than your installed RAM under Mac OS 8.1.

Looking at all the results under OS 9.2.2, using the “next multiple of 32” again provides the best overall VM performance, followed closely by setting VM at twice physical RAM. The old advice to set VM to 1 MB beyond physical RAM only applies if scratch space on your hard drive is extremely limited. Whenever possible, set VM to a multiple of 32 MB.

In the end, if you can run with virtual memory disabled, you may lose some efficiency in the use of available RAM, but you will more than make up for it with the best performance your Mac can manage. Buying enough memory so you can avoid using VM is the best way to squeeze the most performance out of your Mac.